Eva Lichtenberger, an Austrian MEP from the Greens/EFA party, said that some lobby groups had carried out misleading campaigns. She called for anti-fraud commissioner Siim Kallas, who recently launched the European Transparency Initiative, to investigate the activities of patent lobby groups.

"Before today MEPs were bombarded by a fierce and, in cases, deceptive lobbying campaign. We can only guess the identity of the people lurking behind the scenes," said Lichtenberger.

"It is clear that we now need to create a system to control lobbying in the EU. The system must be transparent and make public the interests and funding of the respective lobby groups. We call upon the commissioner for administrative affairs, Siim Kallas, to investigate these problems and make proposals for the necessary action to take," she said.

A spokesman for CompTIA, which had lobbied in favour of the directive, agreed that transparency is essential. "Transparency in any advocacy programme is important to the integrity of the lobbying process. Deceptive lobbying helps no one, least of all MEPs and policymakers needing information upon which they can make informed decisions," he said.

Hartmut Pilch, the president of Foundation for a Free Information Infrastructure (FFII) — which opposed the directive — said he was unhappy with some of the media reporting around the software patent directive.

Pilch cited a Sunday Express article from 5 June which reported that the EU wanted to ban companies from patenting any high-tech device that uses software.

"Abolishing intellectual property sounds very attractive on a superficial level since it will make software cheaper and more widely available. But the implications go far beyond computer software and will damage all of the industries in which Europe leads and that means jobs will be lost," said Simon Gentry of the pro-patent lobby group the Campaign for Creativity, according to the Sunday Express article.

Campaign for Creativity did not respond to a request for comment on the Green Party's call for transparency. Pro-patent lobby groups Intellect and EICTA also failed to respond.

Although some MEPs proposed amendments to the software directive that would have restricted the degree to which software could be patented, these amendments would not have prevented companies from patenting devices that contain software.

While Kallas has suggested that voluntary transparency around lobbying may be sufficient, transparency activists Lobby Control and Corporate European Observatory say that mandatory lobbying disclosure is needed.